Field of the Invention
The present invention relates to a liquid ejecting head for ejecting liquid through an ejection port.
Description of the Related Art
As a printing apparatus for performing printing on a print medium or the like that is widely used at present, an ink jet printing apparatus ejects liquid such as ink from a liquid ejecting head in the form of droplets and lands it on a print medium to form an image or the like. Such an ink jet printing apparatus ejects a fine particulate droplet called ink mist through each of a plurality of ejection ports formed at each of liquid ejecting heads besides droplets (main droplets) landing on a print medium to form an image. After this ink mist is ejected from each of the liquid ejecting heads, the ink mist may float inside of the ink jet printing apparatus without landing on the print medium, and then, adhere to the liquid ejecting head, thereby degrading the function of the liquid ejecting head or shortening the lifetime thereof. In particular, in a case where a large quantity of ink mist adheres onto the liquid ejecting head to coalesce into a large ink droplet, the coalescent ink droplet closes an ejection port, thus raising a problem that deficient ejection is induced to degrade the quality of an image.
In view of the problem, Japanese Patent Laid-Open No. 2011-88103 discloses the configuration in which a suction port arranged outside of a liquid ejecting head sucks air to suck and recover ink mist together with the air.
In addition, Japanese Patent Laid-Open No. H06-155755(1994) discloses forming a conductive thin film on a liquid ejecting head and grounding it, and then, releasing static electricity generated on a nozzle plate via the conductive thin film so as to avoid an ink droplet from being sucked by or adhering onto the nozzle plate. In other words, Japanese Patent Laid-Open No. H06-155755(1994) discloses the technique for forming a conductive thin film at a frictionally sliding surface and grounding it on the understanding that ink mist is adsorbed by static electricity generated by slide friction between the surface of a liquid ejecting head and a wiper member.
However, the techniques disclosed in Japanese Patent Laid-Open No. 2011-88103 and Japanese Patent Laid-Open No. H06-155755(1994) cannot satisfactorily suppress the adhesion of ink mist or dust onto the liquid ejecting head under present circumstances. Specifically, the technique disclosed in Japanese Patent Laid-Open No. 2011-88103 can recover ink mist or dust flowing outward of the surroundings of the liquid ejecting head. However, ink mist or dust produced between the liquid ejecting head and a print medium adheres to an ejection port forming surface of the liquid ejecting head before flowing outward of the surroundings of the liquid ejecting head, thereby inducing contamination of the ejection port forming surface or degrading ejection performance.
Moreover, the technique disclosed in Japanese Patent Laid-Open No. H06-155755(1994) can suppress adhesion of ink mist or dust onto the nozzle plate of the liquid ejecting head whereas it cannot suppress adhesion of ink mist or dust to portions other than the surface of the nozzle plate of the liquid ejecting head. As a consequence, ink mist or dust adhering to the portions other than the surface of the nozzle plate causes contamination or reduced lifetime of the liquid ejecting head.